The Philippines said Wednesday one of its warships is engaged in a standoff with two Chinese surveillance vessels that blocked the arrest of Chinese fishermen in disputed waters of the South China Sea.

The Philippines foreign ministry said the standoff began Tuesday when Manila's flagship naval vessel, the Gregorio del Pilar, confronted eight Chinese fishing boats near a disputed shoal off the northwest province of Zambales.

It said the two Chinese surveillance vessels then positioned themselves between the Philippines Navy ship and the fishing vessels, “preventing the arrest of the erring Chinese fishermen.”

The Philippines summoned Ma Keqing, the Chinese ambassador in Manila, for talks on Wednesday, saying it preferred to resolve the dispute diplomatically. China has not commented on the issue.

Both countries claim ownership of the shoal, which is known as Panatag in the Philippines, and as Huangyan Island in China.

Tensions in the region have risen in recent years as China becomes increasingly assertive about its claims over the entire 3.5 million-square-kilometer South China Sea, which is thought to be rich in oil and gas.

There has been a series of run-ins involving fishermen, military patrols, and other vessels in the disputed waterway, parts of which are also claimed by Vietnam, Malaysia, Brunei and Taiwan.